1. Field of the Invention
This invention relates to novel azo orange pigments, processes for their preparation and to paint, plastic and ink compositions containing such pigments.
2. Description of Related Art
Commercially available orange pigments commonly used in plastics include such pigments as Colour Index (C.I.) Pigment Orange 16 and 34, and Pigment Red 104.
Pigment Orange 16 and 34 are diarylide based pigments. It was reported, however, in R. Az et al, Dyes and Pigments, 15, 1 (1991), that diarylides may degrade to potentially carcinogenic by-products (e.g., 3,3'-dichlorobenzidine) in plastics processed above 200.degree. C., a temperature lower than those used in processing most plastics (e.g., 250-330.degree. C).
Pigment Red 104 is a lead chromate-lead molybdate which of course is undesirable because of its heavy metal content.
Consequently, there is still a need for orange pigments that show improved performance in properties such as color strength, resistance to polar solvent, light fastness and/or heat stability.